I've kept clones in the fridge for several months before rooting them. I take longer cuts, place them in a bag and then seal up. I've noticed that if you're going to store them long term, the cuts and the bags needs to be moisture free. I did notice a smaller percentage rooting the longer you keep them, but I've rooted 85% after 60 days in the crisper.
Edit: I treat them like fresh cuts when I'm ready to root them. A little stem soaking, make your cuts underwater, dip in gel or whatever you use, and place into rapid rooters, jiffy plugs, etc.
I'm sorta doing the same thing now as I'm not growing. Collecting clones in the fridge till I fire up the room again.